Planetary transmission

ABSTRACT

Proposed is a planetary transmission ( 8 ) comprising an internal gear ( 24 ), a sun gear ( 52 ) and a planet carrier ( 10 ), upon which at least one planet gear ( 20 ) is supported. The planetary transmission ( 8 ) possesses a clutch apparatus with a sliding sleeve ( 66 ), which in a first shift-position enables a direct connection between one of the shafts ( 44 ) driving the planetary transmission ( 8 ) and an output shaft ( 12 ) of the planetary transmission ( 8 ). In a second shift-position, the connection of the sliding sleeve ( 66 ) enables a change in the speed of rotation between the driving shaft ( 44 ) and the output shaft ( 12 ) of the planetary transmission ( 8 ). The planet gear ( 20 ) is so supported on the planet carrier ( 10 ), that in case of a shifting from a one shift-position into a respective other shift-position, the planet gear ( 20 ) on the planet carrier ( 20 ) becomes axially slidable.

This application is a national stage completion of PCT/EP2004/005331filed May 18, 2004 which claims priority from German Application SerialNo. 103 26 677.1 filed Jun. 13, 2003.

FIELD OF THE INVENTION

The invention concerns a planetary transmission.

BACKGROUND OF THE INVENTION

Commercial vehicles with a large number of gear positions frequentlypossess an auxiliary range gear train, which acts on the main driveshaft and engages itself with the existing gear stages. With such anauxiliary range gear train, it is possible that the total ratio of themain transmission is increased, since all gear stages of this maintransmission can be employed along with each gear stage of the auxiliaryrange gear train, and in at least one gear stage of the auxiliary rangegear train, the ratio of the gear stages of the main transmission areadjusted to be either under or over their designed ratio.

An auxiliary range gear train for automobiles has been made known by DE41 21 709 A1. With a planet gear arrangement of this kind installedfollowing the main transmission, the possibility exists, of operatingthe motor vehicle within the framework of the gear stages of its maintransmission, respectively, in two different speed ranges. When shiftedinto a first, slow ratio stage of the auxiliary range gear train, theinternal gear of the planetary transmission is coupled by means of aclutch to the transmission housing so that the output shaft of theauxiliary range gear train possesses a lesser speed of rotation thandoes the output shaft of the main transmission. In a second shiftingstage, a direct through-drive from the output shaft of the maintransmission onto the output shaft of the auxiliary range transmissionis effected, whereby a clutch establishes a direct connection betweenthe output shaft of the main transmission and the output shaft of theauxiliary range gear train. The shifting mechanism to carry this out isexpensive in its design and fabrication.

As a further development, DE 198 51 895 A1 teaches an auxiliary rangegear train constructed as a planet gear system. In this case, theinternal gear of the planet gearing is non-rotatably bound to thehousing of the transmission. The sun gear of the planetary transmissionis coaxially aligned to the output shaft of the main transmission and,compared to the output shaft of the main transmission, it is free in itsrotation. For the construction of a step-down ratio between the outputshaft of the main transmission and the output shaft of the auxiliaryrange gear train, the sun gear can be non-rotatably bound with theoutput shaft of the main transmission. Once again, this design iscomplex, expensive in design and time consuming. Furthermore, theindividual components raise problems with regard to support.

Thus the invention has the purpose of improving a planetary transmissionand especially improving the component structure of the bearing support.

SUMMARY OF THE INVENTION

A planetary transmission comprising an internal gear, a sun gear and aplanet carrier, upon which at least one planet gear is supported,possesses a clutch featuring a sliding sleeve which, in one stagesuitable for one gear position, establishes a direct connection betweena shaft driving the planetary transmission and an output shaft of theplanetary transmission. In a shifting position, other than that above, aspeed of rotation change is effected between the driving shaft and theoutput shaft of the planetary transmission. The planet gear is somounted on the bearing of the planet carrier, that upon a shifting fromone given stage into a respective successive stage, the planet gear onthe planet carrier is axially displaceable. Normally, in a planetarytransmission of this design, three or five planet gears are to be foundwhich are distributed about the circumference thereof.

Advantageously, relative to the internal gear and to the sun gear, theplanet gear is axially affixed so that an axial sliding of the planetgear simultaneously enables, an axial sliding of the internal gear andthe sun gear.

In the case of a particularly advantageous embodiment, the planet gearexperiences a smaller return displacement than does the sliding sleeve,when sliding from the one gear position into the respective nextposition, which impels the planet gear.

In one advantageous embodiment, the sliding sleeve has the capability ofmoving the sun gear axially and thereby the planet gear on the planetcarrier, likewise, slides axially.

One design example of the present invention shows the sun gearaccompanied by a pressure bolt, which coacts with the sliding sleeve,even though, in another embodiment, the sliding sleeve and the sun gearare constructed together as a one-piece component.

Advantageously, both the internal gear as well as the sun gear possesstoothed pressure compensators which adjoin the planet gear.

In another embodiment, the sliding clutch has a neutral position, whichlies between the two shift-positions and by which the output shaft ofthe planetary transmission is not driven.

A further advantageous embodiment of the invention shows the planet gearon the planet carrier running in a roller bearing. Advantageously, theroller bearing has a multi-row design. The combined relative support ofthe sun gear plus the driving gear of the planetary transmission,likewise, form a possibility for another embodiment design.

The planetary transmission presents itself especially advantageous hereas an auxiliary range gear of a motor vehicle, which is designed as atorque transmitting drive string interlocked to a main transmission. Bythis addition, the output shaft of the main transmission forms thedriving shaft of the planetary gear transmission.

Likewise, as an exceptionally advantageous embodiment, the maintransmission comprises two countershafts and one floating principalshaft supported between the countershafts, which serves as an output ofthe main transmission which, in turn, forms the input shaft of theplanetary gear transmission and which, at its end, is supported by thesun gear of the planetary transmission.

Advantageously, the bearing of the end of the main drive shaft includesa pin with a slotted profile.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example, with referenceto the accompanying drawings in which:

FIG. 1 is a planetary transmission with a first shifting apparatus in aneutral position;

FIG. 2 is the shifting apparatus according to FIG. 1 in a first gearposition;

FIG. 3 is the shifting apparatus according to FIG. 1 in a secondshifting position; and

FIG. 4 is a planetary transmission with a second shifting apparatus in aneutral position.

DETAILED DESCRIPTION OF THE INVENTION

In a transmission housing 4 of a vehicle, a shifting transmission 2possesses a main transmission 6 and thereon, an auxiliary range gearingin the form of a planetary transmission 8. The planetary transmission 8includes a planet carrier 10, which is designed as a common componentwith an output drive 12 of the shifting transmission 2. About the outputdrive shaft 12 is a flange 14 and the output drive 12 is supported by abearing arrangement 16 in the transmission housing 4. The planet carrier10 has several, evenly distributed planet bolts 18 about itscircumference. Of these planet bolts 18, in the illustrations, only onebolt is shown. On the planet bolt 18, supported by a roller bearing 22,is shown only one planet gear 20. Distributed orderly about thecircumference of the planet carrier 10 would normally be three or fivesuch planet gears 20. The roller bearing 22 is constructed as a doublerow, cylindrical roller bearing or an equivalent needle bearing. Theplanet gear 20 is externally encompassed by an internal gear 24, whichexhibits a shift toothing 26. The shift toothing 26 engages itself in abase plate 30. The base plate 30 is held in non-rotatable fashion in thetransmission housing 4. In this arrangement, the base plate 30 can becast into the transmission housing 4, or be clamped between theindividual elements of the transmission housing 4 as a separate plate. Ashaft 32 serves as the possible drive of an auxiliary power take-off andis supported by a bearing arrangement 34 in the transmission housing 4.

The planet carrier 10 has a projection 36 located on that side of theplanetary transmission 8 which is opposite to the output drive shaft 12,on which the planet carrier 10 is held by a roller bearing 38 in thetransmission housing 4. Also, a countershaft 40 of the main transmission6 is supported in a bearing arrangement 42 in the transmission housing4. A main drive shaft 44 of the main transmission 6 carries a toothedgear 46 on its end for the reverse gear ratio. The gear 46 is placed onthe main drive shaft 44 with allowance for small radial play. This lightplay is typical for a shifting transmission with a power branching intotwo countershafts. At the end of the main drive shaft 44 is provided apin 45, which exhibits a slotted profile. The pin 45 includes a pressurebolt 48, which is pressed in an outward direction by a spring 50. Onthis account, the pressure bolt 48 extends itself through a sun gear 52of the planetary transmission 8, which has been placed on the pin 45 ofthe main drive shaft 44, whereby the main drive shaft 44 bases itself inthe sun gear 52. Between the sun gear 52 and the output drive shaft 12,i.e., the planet carrier 10, is placed a shell 54 with a disk. Thisarrangement allows a common fitting and a mutual sliding between the sungear 52 on the output drive shaft 12. Accordingly, the speed of rotationof the sun gear 52 and that of the output drive shaft 12 need not be thesame.

On the sun gear 52 are two toothed pressure compensators 56 and 58,which restrict any axial movement of the planet gear 20 relative to thesun gear 52. However, in this connection, a contact of the planet gear20 against the toothed pressure compensators 56, 58 is allowed, in orderto pick up an axially directed force, which said force results frominclined toothing of the planetary transmission 8. Two additionaltoothed pressure compensators 60 and 62 are placed radially within theinternal gear 24 and again permit a contacting meeting of the planetgear 20. The two toothed pressure compensators 60 and 62 restrict anaxial movement of the planet gear 20 relative to the internal gear 24.By way of this arrangement of the toothed pressure compensators 56, 58,60 and 62, the sun gear 52, the planet gear 20 and the internal gear 24move themselves as a packet. This unified movement is such that an axialmovement, introduced by the sun gear 52, and transferred by the planetgear 20 results in an equally directed axial movement of the internalgear 24.

In FIG. 1, the pressure bolt 48 coacts with a detent 64, i.e., a holdingmeans, within a sliding sleeve 66 and thereby engage the detent 64. Bythis means, the sliding sleeve 66 is held in a neutral position. Thesliding sleeve 66 has a first internal toothing 68 (FIG. 2), whichengages itself in an external toothing 70 on the sun gear 52 and anon-rotatable connection between the sliding sleeve 66 and the sun gear52 is established (see FIG. 2). For the formation of a non-rotatableconnection between the sliding sleeve 66 and the main drive shaft 44,the sliding sleeve 66 has a second internal toothing 72, which engagesitself in an external toothing 74 on the main drive shaft 44.

For the bringing about of an optional, non rotatable connection of themain drive shaft 44 with the planet carrier 10 for the formation of adirect binding of the main transmission 6 with the output drive shaft 12at a continuing equal speed of rotation, the sliding sleeve 66 has ashift-toothing 76, which can engage itself in a shift toothing 78 on theprojection 36 of the planet carrier 10.

FIG. 1 presents the planetary transmission 8 in a neutral position.Neither the shift-toothing 26 and 28, nor the shift-toothing 76 and 78engage each other.

The pressure bolt 48 enters into the detent 64 on the sliding sleeve 66.The sun gear 52 finds itself positioned to the right (as seen in thedrawing). The planet gear 20 is supported on the planet bolt 18 only ona cylindrical roller bearing of the roller bearing 22. The planetarytransmission 8 is load free, hence a simple bearing suffices, whichbrings about a small loss.

If now the sliding sleeve 66 is pushed to the left by an actuator (notshown in the drawing), then the sliding sleeve 66, likewise, draws thesun gear 52 to the left by actuating a ring 80 left being in accord withthe drawing. This motion is described in FIG. 2. The planet gear 20 is,likewise, moved and accompany therewith by the toothed pressurecompensators 56 and 58 and, in turn, brings the internal gear 24 to theleft along with it, powered by the toothed pressure compensators 60 and62. By this action, the two shift toothings 26 and 28 engage each other,whereby the internal gear 24 becomes non-rotatably affixed. Thereby, theplanet carrier 10 turns in a known manner, as compared to the main driveshaft 44 in a slower ratio. At this point, the planetary transmission 8is under a loaded condition, because the total torque is now being takenover by the planet gear 20. On this account, it is necessary, that thebearing support of the planet gear 20 be reinforced by the planet bolt18. Due to the sliding of the planet gear 20 to the left by the sun gear52, the planet gear 20 is also drawn onto the second cylindrical rollerbearing of the roller bearing support 22. The situation now is that aclearly increased load capacity of the roller bearing support 22 is madeavailable. Instead of several cylindrical roller bearings, a multi-rowbearing can be considered, in particular, a two-row needle bearing.

If now, the sliding sleeve 66, as illustrated in FIG. 2, is pushed tothe right by the (unseen) actuator, then the sliding sleeve 66 moves thesun gear 52, likewise, to the right (per the drawing) by way of thedetent 64 and the pressure bolt 48. The planet gear 20 is pushed by thetoothed pressure compensators 56 and 58 onto the sun gear 52 and ofitself then pushes, the internal gear 24 to the right into the neutralposition by way of the toothed pressure compensators 60 and 62 accordingto FIG. 1. At this point, the sun gear 52 with the shell 54 lies againstthe planet carrier 10.

If the sliding sleeve 66 is caused to move to the right out of theneutral position (FIG. 1), then the force of the spring 50 on thepressure bolt 48 is overcome by the detent 64 and the sliding sleeve 66moves further to the right. When this occurs, the sun gear 52 is notcomplementarily moved axially. On this account, the sun gear 52 andtherewith the planet gear 20 slidingly cover a small path back, as doesthe sliding sleeve 66 which moves the sun gear 52 and therewith theplanet gear 20. The shift toothing 76 on the sliding sleeve 66 engagesthe complementary shift toothing 78 on the projection 36 of the planetcarrier 10, whereby a non-rotatable connection between the main driveshaft 44 and the output drive shaft 12 is achieved. This is presented inFIG. 3. Thereby, in a known way, the planet carrier 10 turns itself inreference to the main drive shaft 44 at the same speed of rotation. Nowthe planetary transmission 8 runs free from load, while the total torqueis taken over by the planet carrier 10. The bearings of the planet gear20 on the planet bolt 18 must not be supported, so that the planet gear20 can be carried only on a cylindrical roller bearing of the rollerbearing 22 as is the case in the neutral position.

FIG. 4 illustrates a changed design of the sliding sleeve 66. In thiscase, the sliding sleeve 66 is constructed as being of one part with thesun gear 52. In this arrangement, during an axial sliding of the slidingsleeve 66, within the three possible shift positions, the sun gear 52and therewith the planet gear 20 and the internal gear 24 always move incommon. On this account, it is necessary that sufficient operationalspace be made available in the planetary transmission 8.

The attainment of the slow ratio is carried out as is explained inregard to FIG. 2. By means of the one piece design of the sliding sleeve66 and the sun gear 52, the pressure bolt and the detent can beeliminated. If now the sliding sleeve 66 is pushed to the right, (perdrawing) by an actuator and out of the shifting position for the slowratio, then the sliding sleeve 66 necessarily pushes the attached sungear 52 with it, likewise to the right. The planet gear 20 slides along,being pushed by the toothed pressure compensators 56 and 58 on the sungear 52 and, on its own, pushes the internal gear 24 with the aid of thetoothed pressure compensators 60 and 62. As this occurs, the internalgear 24 moves to the right until the neutral position shown in FIG. 4 isreached. The sun gear 52 does not lie on the planet carrier 10.

If the sliding sleeve 66 is pushed further to the right out of theneutral position (shown in FIG. 4), then accordingly, the sleeve 66 alsoaxially pushes the sun gear 52 to the right. The shift toothing 76 onthe sliding sleeve 66 engages in the shift toothing 78 on the projection36 of the planet carrier 10, whereby a non-rotatable connection isbrought about between the main drive shaft 44 and the output drive shaft12. The planetary transmission 8 runs free of load again, because theentire torque is taken over by the planet carrier 10. The support of theplanet gear 20 on the planetary bolt 18 must not be reinforced, so thatthe planet gear 20, as is the case in the neutral position, can becarried only by a cylindrical roller bearing of the roller bearing 22.

For the formation of a stable end position, and for the avoidance of anundesirable problematic sliding, it is possible that the toothing 26, 28and 76 to 78 be designed with a roll-back.

By way of the arrangement, according to the invention, a dog-clutch typeshifting device is formed for a planetary transmission which is placedon the main drive shaft of the transmission. The shifting of the rapidratio of the auxiliary range gear train by direct connection is donefree of load. The short shifting path of the toothings on the auxiliaryrange gear train enables short operating levers on the planetary bolts.Roll bearings carry the planet gears safely on the planetary bolts.

Fundamentally, the invented shifting apparatus is adaptable, both for ashifting transmission with one countershaft as well as for a shiftingtransmission with a load splitter requiring several countershafts.

REFERENCE NUMERALS

-   2 shifting transmission-   4 transmission housing-   6 main transmission-   8 planetary transmission-   10 planet carrier-   12 output drive shaft-   14 flange for 12-   16 bearing arrangement-   18 planet bolt-   20 planet gear-   22 roller bearing-   24 internal gear-   26 shift toothing-   28 shift toothing-   30 support base plate-   32 shaft-   34 bearing arrangement-   36 projection-   38 roller bearing-   40 countershaft-   42 bearing arrangement-   44 main drive shaft-   45 pin-   46 gear-   48 pressure bolt-   50 spring-   52 sun gear-   54 shell-   56 toothed pressure compensator-   58 toothed pressure compensator-   60 toothed pressure compensator-   62 toothed pressure compensator-   64 detent-   66 sliding sleeve-   68 internal toothing-   70 external toothing-   72 internal toothing-   74 external toothing-   76 shift toothing-   78 shift toothing-   80 ring

1. A planetary transmission (8), comprising an internal gear (24), a sungear (52) and a planet carrier (10), upon which at least one planet gear(20) is mounted and which possesses a clutch having a sliding sleeve(66), which, in a first shifting position enables a direct connectionbetween one shaft (44) which drives the planetary transmission (8) andan output shaft (12) of the planetary transmission (8), and in a secondshifting position, enables a change in the speed of rotation between themain drive shaft (44) and the output shaft (12) of the planetarytransmission (8), the planet gear (20) is supported such that the planetcarrier (10), when shifting from a one shift-position into an othershift-position, the planet gear (20) on the planet carrier (10) axiallyslides.
 2. The planetary transmission (8) according to claim 1, whereinthe planet gear (20) is axially affixed relative to the internal gear(24) and to the sun gear (52), such that are an axial sliding of theplanet gear (20) enables a simultaneous axial sliding of the internalgear (24) and the sun gear (52).
 3. The planetary transmission (8)according to claim 1, wherein the sliding sleeve (66) has the capabilityof moving the sun gear (52) axially and therewith the ability to axiallyslide the planet gear (20) on the planet carrier (10).
 4. The planetarytransmission (8) according to claim 1, wherein by sliding the planetgear (20) from a one shift-position into an other shift-position, theplanet gear (20) travels a smaller sliding path back, than that of thesliding sleeve (66) which moves the planet gear (20).
 5. The planetarytransmission (8) according to claim 1, wherein the sun gear (52)includes a pressure bolt (48), which coacts with the sliding sleeve(66).
 6. The planetary transmission (8) according to claim 1, whereinthe sliding sleeve (66) and the sun gear are constructed in one piece.7. The planetary transmission (8) according to claim 1, wherein both theinternal gear (24) as well as the sun gear (52) possess toothed pressurecompensators (56, 58, 60, 62) which lie adjacent to the planet gear(20).
 8. The planetary transmission (8) according to claim 1, whereinthe clutch possesses a neutral position, which lies between the twoshift-positions and in which the output shaft (12) of the planetarytransmission (8) is not driven.
 9. The planetary transmission(8)according to claim 1, wherein the planet gear (20) on the planetcarrier (10) is supported by a roller bearing (22).
 10. The planetarytransmission (8) according to claim 9, wherein the roller bearing (22)includes a multi-row bearing.
 11. The planetary transmission (8)according to claim 1, wherein the sun gear (52) and the main drive shaft(44) of the planetary transmission (8) are supported relative to oneanother.
 12. The planetary transmission (8) according to claim 1,wherein a support at the end of the main drive shaft (44) includes a pin(45) with a slotted profile.
 13. The planetary transmission (8)according to claim 1, wherein the planetary transmission (8) ispresented as an auxiliary gear train, which is designed as a torquetransmitting drive string connected to a principal gear drive (6) and bywhich the output shaft (44) of a principal gear drive (6) forms adriving shaft of the planetary transmission (8).
 14. The planetarytransmission (8) according to claim 1, wherein the principal gear drive(6) includes two countershafts (40) and one bearing supported main driveshaft (44) which floats between the two countershafts (40), which formsthe output shaft of the principal gear drive (6) and which in turn formsthe driving shaft of the planetary transmission (8) and which, on an end(46) is supported in the sun gear (52) of the planetary transmission(8).